
function getToday() {
	// 今天
	var today = new Date();
	today.setHours(0);
	today.setMinutes(0);
	today.setSeconds(0);
	today.setMilliseconds(0);
	alert(today);
	var oneday = 1000 * 60 * 60 * 24;
	// 昨天
	var yesterday = new Date(today - oneday);
	alert(yesterday);
	// 上周一
	var lastMonday = new Date(today- oneday * (today.getDay() + 6));
	alert(lastMonday);
	// 上个月1号
	var lastMonthFirst = new Date(today - oneday * today.getDate());
	lastMonthFirst = new Date(lastMonthFirst - oneday * (lastMonthFirst.getDate() - 1));
	alert(lastMonthFirst);
}

/**
 * 日期格式化:new Date().format('yyyy-MM-dd hh:mm:ss')
 * @param format
 * @returns
 */
Date.prototype.format = function(format){
    var o = {
        "M+" : this.getMonth()+1, //month
        "d+" : this.getDate(),    //day
        "h+" : this.getHours(),   //hour
        "m+" : this.getMinutes(), //minute
        "s+" : this.getSeconds(), //second
        "q+" : Math.floor((this.getMonth()+3)/3),  //quarter
        "S" : this.getMilliseconds() //millisecond
    };
    
    if(/(y+)/.test(format)){
    	format=format.replace(RegExp.$1,(this.getFullYear()+"").substr(4 - RegExp.$1.length));
    }
    
    for(var k in o){
    	if(new RegExp("("+ k +")").test(format)){
    		format = format.replace(RegExp.$1,RegExp.$1.length==1 ? o[k] : ("00"+ o[k]).substr((""+ o[k]).length));
    	}
    }
    
    return format;
};
